Interestingly, the population argument is not listed among those that "Answers in Genesis" recommends that YECs should not use.Interestingly, the population argument is not listed among those that "Answers in Genesis" recommends that YECs should not use.

Evolutionists claim that mankind evolved from apes about a million years ago. If the population had grown at just 0.01% per year since then (doubling only every 7,000 years), there could be 10^43 people today—that’s a number with 43 zeros after it. This number is so big that not even the Texans have a word for it! To try to put this number of people in context, say each individual is given ‘standing room only’ of about one square metre per person. However, the land surface area of the whole Earth is ‘only’ 1.5 x 10^14 square metres. If every one of those square metres were made into a world just like this one, all these worlds put together would still ‘only’ have a surface area able to fit 10^28 people in this way. This is only a tiny fraction of 10^43 (10^29 is 10 times as much as 10^28, 10^30 is 100 times, and so on). Those who adhere to the evolutionary story argue that disease, famine and war kept the numbers almost constant for most of this period, which means that mankind was on the brink of extinction for most of this supposed history.10 This stretches credulity to the limits.

30. World Population Growth Rate -- In recent times is about 2% per year. Practicable application of growth rate throughout human history would be about half that number. Wars, disease, famine, etc. have wiped out approximately one third of the population on average every 82 years. Starting with eight people, and applying these growth rates since the Flood of Noah's day (about 4500 years ago) would give a total human population at just under six billion people. However, application on an evolutionary time scale runs into major difficulties. Starting with one "couple" just 41,000 years ago would give us a total population of 2 x 10 to the89th. The universe does not have space to hold so many bodies.

One thing that you might mention is that these sort of calculations which very quickly generate impossibly high populations are an important foundation of Darwin's concept of natural selection.